The present invention relates to a flow restrictor. As is well known flow restrictors are one of the main components of trickle or drip irrigation systems. The purpose of a flow restrictor is to retard the flow within a predetermined conduit and thereby to reduce the pressure from the head of the source of irrigation water. As a consequence the flow is emitted in the form of a very slow trickle or dropwise. The purpose of these devices -- which are also known as "drip emitters" or "trickle emitters" -- is to economize in water expenditure and to supply the water in a steady, slow trickle to the point where it is actually needed by the plants or cultures to be irrigated.